Advertisements
Advertisements
A geneticist interested in studying variations and patterns of inheritance in living beings prefers to choose organisms for experiments with shorter life cycle. Provide a reason.
Concept: Mendelian Inheritance - Mendel’s Law of Heredity
A teacher wants his/her students to find the genotype of pea plants bearing purple coloured flowers in their school garden. Name and explain the cross that will make it possible
Concept: Extensions of Mendelian Genetics (Deviation from Mendelism) > Polygenic Inheritance
"Determination of Biological Oxygen Demand (BOD) can help in suggesting the quality of a water body." Explain.
Concept: Introduction of Water Pollution and Its Control
Since October 02, 2014 "Swachh Bharat Abhiyan" has been launched in our country.
(a) Write your views on this initiative giving justification.
(b) As a biologist name two problems that you may face while implementing the programme in your locality.
(c) Suggest two remedial methods to overcome these problems.
Concept: Environmental Issues
Since October 02, 2014 "Swachh Bharat Abhiyan" has been launched in our country.
(a) Write your views on this initiative giving justification.
(b) As a biologist name two problems that you may face while implementing the programme in your locality.
(c) Suggest two remedial methods to overcome these problems.
Concept: Environmental Issues
Explain the genetic basis of blood grouping in human population.
Concept: Extensions of Mendelian Genetics (Deviation from Mendelism)
In Snapdragon, a cross between true-breeding red flowered (RR) plants and truebreeding white flowered (rr) plants showed a progeny of plants with all pink flowers.
The appearance of pink flowers is not known as blending. Why?
Concept: Extensions of Mendelian Genetics (Deviation from Mendelism)
In Snapdragon, a cross between true-breeding red flowered (RR) plants and truebreeding white flowered (rr) plants showed a progeny of plants with all pink flowers.
What is this phenomenon known as?
Concept: Extensions of Mendelian Genetics (Deviation from Mendelism)
Write the scientific name of the fruit-fly. Why did Morgan prefer to work with fruit-flies for his experiments? State any three reasons.
Concept: Genetic Disorders
Linkage and crossing-over of genes are alternatives of each other. Justify with the help of an example.
Concept: Linkage and Crossing Over
Identify 'a', 'b', 'c',’d’, 'e' and 'f' in the table given below:
| No. | Syndrome | Cause | Characteristics of affected individuals | Sex Male/Female/Both |
| 1. | Down's | Trisomy of 21 | 'a' (i) (ii) |
'b' |
| 2. | 'c' | XXY | Overall masculine development. |
'd' |
| 3. | Turner's | 45 with XO | 'e' (i) (ii) |
'f' |
Concept: Genetic Disorders
Plenty of algal bloom is observed in a pond in your locality.
(a) Write what has caused this bloom and how does it affect the quality of water.
(b) Suggest a preventive measure.
Concept: Introduction of Water Pollution and Its Control
During a medical investigation, an infant was found to possess an extra chromosome-21. Describe the symptoms the child is likely to develop later in the life.
Concept: Genetic Disorders
Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident's Welfare Association of your locality organized an awareness programme entitled "Bury not burn". They invited you, being a biology student to participate.
(a) How would you justify your arguments that promote burying and discourage burning? (Give two reasons)
(b) With the help of flow charts, one for each practice depict the chain of events that follow.
Concept: Effects of Domestic Sewage and Industrial Effluents on Water
Mention one limitation of the electrostatic precipitator.
Concept: Prevention of Air Pollution
Assertion (A): In Thalassemia an abnormal myoglobin chain is synthesized due to a gene defect.
Reason (R): α-Thalassemia is controlled by genes HBA-1 and HBA-2 on chromosome 16.
Concept: Genetic Disorders > Mendelian Genetics
|
The chromosome number is fixed for all normal organisms leading to species specification whereas any abnormality in the chromosome number of an organism results into abnormal individuals. For example, in humans, 46 is the fixed number of chromosomes both male and female. In males it is '44 + XY' and in females, it is '44 +XX'. Thus the human male is heterogametic, in other words produces two different types of gametes one with '22 + X' chromosomes and the other with '22 + Y' chromosomes respectively. Human female, on the other hand, is homo gametic i.e. produce only one type of gamete with '22 + X' chromosomes only. Sometimes an error may occur during the meiosis of the cell cycle, where the sister chromatids fail to segregate called nondisjunction, leading to the production of abnormal gametes with altered chromosome numbers. On fertilisation, such gametes develop into abnormal individuals. |
(a) State what is aneuploidy. (1)
(b) If during spermatogenesis, the chromatids of sex chromosomes fail to segregate during meiosis, write only the different types of gametes with altered chromosome numbers that could possibly be produced. (1)
(c) A normal human sperm (22 + Y) fertilises an ovum with karyotype '22 +XX'. Name the disorder the offspring thus produced would suffer from and write any two symptoms of the disorder. (2)
OR
(c) Name the best-known and most common autosomal aneuploid abnormality in humans and write any two symptoms. (2)
Concept: Genetic Disorders > Chromosomal Abnormalities
What is a cistron?
Concept: Protein Synthesis > Transcription Unit and the Gene
Explain the process of DNA replication with the help of a schematic diagram.
Concept: DNA Replication > The Experimental Proof
In which phase of the cell cycle does replication occur in Eukaryotes? What would happen if cell-division is not followed after DNA replication.
Concept: DNA Replication > The Experimental Proof
